The Airports Commission Report: Carbon Emissions, Air Quality and Noise Contents

3Air Quality


31.The impact of air pollutants on human health has increased in profile over the last few years. Partly this has been due to growing scientific evidence about the level of harm that pollutants such as nitrogen oxides (NOx) can cause.40 It is also due to increasing awareness of the level of these pollutants emitted by modern diesel vehicles as discussed at our recent hearings on Diesel Emissions and Air Quality.

32.Air quality in the UK is regulated by a series of international agreements and domestic law. These were detailed by Heathrow ltd. in their written evidence and are also discussed by the Airports Commission in their report.41 The Commission found:

Even with additional runway capacity in place, none of the air quality receptors around Heathrow which would have implications for human health, such as at schools or residential buildings, are forecast to exceed air quality limits in 2030.42

33.However, the Commission did find that a third runway could, without mitigation, result in up to 47,000 homes around Heathrow experiencing higher nitrogen dioxide (NO2) levels. Whilst the Commission observed that the number moving into the “at risk” category would be “very small” (14), Hounslow Council pointed to preliminary work done by the Commission’s consultants estimating costs of between £2.8 million and £10.8 million in additional medical appointments resulting from worsening air quality.43 Before the Government makes its decision, it should make its own assessment of the likely costs of preventing an adverse impact on health from expansion at Heathrow and publish it.

The Clean Air Directive

34.Although the Commission discussed a number of international agreements relating to air quality, its concerns and the evidence we received, focused almost entirely on the emission of NOx (specifically NO2) in relation to UK compliance with EU Directive 2008/50/EC on ambient air quality and cleaner air for Europe (“the Directive”).

35.The Directive limits values in respect of certain key pollutants - including an annual mean limit value of 40 μg/m3 NO2.44 Compliance is assessed through measurements carried out by “receptors” placed at the high-polluting areas within the region (subject to certain exemptions relating to work places, the carriageways of roads and areas where people do not normally access). A region is deemed to be in breach of the Directive if receptors exceed the limit values. The deadline for compliance was 2010 but a number of areas in the UK remain above the limit values, including Greater London.45 At the time the Commission’s report was being finalised, the Greater London region was not forecast to be compliant with the directive until 2030 - in line with the Government’s air quality strategy of the time.46

Heathrow and the Commission’s Findings

36.John Holland-Kaye told us:

Heathrow today complies with EU air quality limits. It is an issue we take very seriously. We have a very good and robust plan in place to make sure that even with expansion we will continue to do that. We have some mitigating factors we can take.47


There are two monitoring stations on the M4 to the north of Heathrow that are higher than the 40 measure. The reason for that is through traffic on the M4. The real issue for air quality is vehicle traffic, not the airport. In terms of those two monitoring stations, DEFRA forecast that they will both be compliant by 2020.48

37.However, the Commission did find that Heathrow expansion could result in a breach of EU limits. It is worth quoting the Commission’s findings in full, as their interpretation of the Directive was criticised in the evidence we received:

In order for the Commission to determine that a scheme can be delivered in compliance with the Air Quality Directive, it would require assurance that the scheme would not delay the date by which the sector within which the scheme was located would reach compliance with the limits set out within the Directive. In the case of the Heathrow schemes, the relevant sector is the Greater London Agglomeration area. It would therefore need to be demonstrated that, by 2030, receptors in the vicinity of the expanded airport site would not report the highest concentrations of NO2 in the sector. Without Heathrow expansion, the Marylebone Road is expected to report the highest concentrations in 2030.

The Commission’s dispersion modelling has shown that using pessimistic assumptions and without actions to mitigate emissions, both of the Heathrow schemes would result in NO2 concentrations on the Bath Road in 2030 which would be higher than those on the Marylebone Road. Therefore, absent mitigation, both schemes would delay compliance with the Directive and hence would not be deliverable within the legal framework.49

38.The Commission and Heathrow ltd. both believed that, with additional mitigation measures, the sites on Bath Road could be brought below the level of Marylebone Road by 2030. Heathrow ltd. argued it would be lower purely on existing measures - but was prepared to consider additional mitigation despite this.50 In its supplementary written evidence Heathrow ltd. broke its mitigating measures into three - a package of measures to improve surface access to the airport, a package of measures relating to the use of aircraft and a further package of measures that the Airports Commission suggested might be necessary.51

39.The Commission recommended:

Firm action will be needed on the part of the airport operator to ensure that emissions related to the airport are minimised, together with an effective national strategy to address broader background air quality issues primarily associated with road traffic. Any new capacity should only be released when it is clear that air quality around the airport will not delay compliance with EU limits.52

Criticisms of the Commission’s Findings

Interpretation of Compliance

40.We received a number of submissions that were critical of the Commission’s decision to define compliance with reference to the performance of central London. Richard di Cani, of TfL, said:

The Commission has adopted a particular interpretation of EU guidance, which basically allows air quality to get worse provided it is no worse than the worst link in the zone, and that is the assessment they have adopted. The proposals do not improve air quality anywhere. They make it worse. As a basic approach we would disagree with their interpretation of the guidance that they have adopted.53

41.Daniel Moylan argued that road schemes in London were evaluated against a requirement that the scheme should not cause air quality to deteriorate and that this should be the minimum standard.54 Clean Air in London took the view, and commissioned a Q.C.’s opinion in support of it, that the Directive prohibits actions that would significantly deteriorate air quality within a zone that was already in breach of the limit values.55

42.Sir Howard stated the Commission had also taken legal advice and believed that its interpretation of the Directive was the correct one.56 Phillip Graham denied that the approach taken by the Commission implied the limit values would not be met. He argued that the Commission had used Marylebone Road as a measure by which to ascertain the likelihood of Bath Road being compliant.57

43.Many of our witnesses interpreted the Commission’s interpretation of the Air Quality Directive as implying that significant increases in NO2 resulting from Heathrow expansion would be allowable because of worse performance elsewhere in London. This would make no sense in terms of protecting public health and wellbeing. The Government should make clear that this is not the position it intends to take when assessing the scheme for compliance with the Directive.


44.Critics of expansion argued that the Commission’s use of 2030 as the point of analysis was mistaken. The Supreme Court ruled in April 2015 that the Government had to consult on a new air quality strategy. This plan was published by the Department for Environmental, Food and Rural Affairs (DEFRA) in September 2015 and forecast compliance within London by 2025.58 Client Earth, who bought the Supreme Court case, argued that the Commission was therefore evaluating compliance against a target that had been found to be unlawful.59

45.At the other end of the scale, several residents argued that compliance should also be measured in 2050, when the airport would be operating at full capacity. Their view was that it was unfair to calculate the economic benefits of expansion on the basis of full capacity whilst only calculating environmental impacts based on less than full capacity.60 Richard di Cani, of TfL, agreed:

The Davies Commission has tested a particular scenario in terms of Heathrow demand in 2030, based on certain assumptions around passenger movement, employees and mode splits. We would normally, for something so significant, look beyond the year of opening to a full utilisation and test that in a number of different scenarios so we can see the best and the worst case from it.61

46.Sir Howard was open to the idea that the new air quality strategy might require reconsideration of the air quality picture. Although he had not studied the DEFRA consultation in depth, he believed that additional Government measures to improve air quality would improve the chances of compliance from an expanded Heathrow.62

47.Before the Government makes its decision, it will need to demonstrate that its revised air quality strategy can deliver compliance with legal pollution limits within the timescales agreed in the finalised plan to be approved by the European Commission. It will also need to show that this can be maintained even when the expanded airport is operating at full capacity. Heathrow’s existing air quality strategy should also be revised to meet the new targets. Failing this, Heathrow should not be allowed to expand.


48.As described above, the Commission recommended that slots at an expanded Heathrow should only be released once it could be shown that the area around Heathrow would not delay compliance with the Directive. Heathrow have expressed their willingness to abide by this condition and confidence that it could be met.63

49.Several witnesses expressed doubts as to how enforceable this would be in practice. Manchester Airports Group stressed the complexity of disaggregating the various polluting factors around an airport - a subject we return to below - and argued this created a degree of uncertainty which would be difficult to manage.64 The 2M Boroughs also pursued this theme, raising the prospect that capacity might be built and then unused.65 Hounslow Council questioned whether, in such circumstances, Government would be willing to hold Heathrow to the standards that had been set.66

50.The Commission recommended that the release of capacity at an expanded airport should be conditional on air quality standards being met. The Government should not approve expansion at Heathrow until it has developed a robust framework for delivery and accountability. This should have binding, real-world milestones and balance the need for investor certainty with assurances that a successor Government cannot set the conditions aside if they become inconvenient.


51.As noted above, the immediate vicinity of Heathrow complies with the EU standards. The breaches of limit values take place around nearby roads. Heathrow ltd. argued in their written evidence that the airport accounts for only a relatively small proportion of the traffic, and therefore of the NO2, in the surrounding area. For example, they provided figures suggesting that only 16% of NO2 recorded at Hillingdon - 2km north of the airport - could be attributed to the airport or airport-related traffic.67 John Holland-Kaye told us that one of the receptors at Bath Road would still be in breach of EU standards even if the airport did not exist.68

52.The local authorities however, argued that Heathrow was already unsustainable in terms of air quality because of its role in contributing to already congested roads.69 Hounslow Council and others argued that the Commission’s condition on the release of capacity at Heathrow should go further afield:

It would be relatively easy for the owners of the Airport to achieve compliance within or close to their own boundaries by, for example, using electric vehicles for terminal activities or by employing a congestion charging scheme at their perimeter. But such measures would not of themselves improve air quality in Boroughs such as ours which are affected by petrol and diesel powered road vehicles running to and from the airport as well as by pollution from aircraft overflying us. Indeed, some of the proposed mitigation measures outlined by the promoter such as an alternative congestion charging zone could simply result in an increase in congestion on the road network in our Borough through traffic displacement.70

53.Disaggregating the impacts of Heathrow on local traffic, and therefore air quality, is complex and contested by the airport and the local authorities. The Government must establish clearly delineated responsibilities for meeting air quality limits before deciding to go ahead with the scheme. We foresee significant legal and commercial risks further down the line if this is not done, for example, if central Government tried to hold local authorities to account for a failure to meet the targets that they attributed to airport expansion or to penalise the airport for pollution that it attributed to background traffic.

Surface Transport

54.Road access to the airport was considered by many of our witnesses (and the Commission itself) to be the key factor in determining the impact of expansion on air quality.71 The Commission recommended:

Heathrow Airport Ltd. must be held to performance targets to increase the percentage of employees and passengers accessing the airport by public transport, reducing pressure on local roads and air quality. The introduction of a congestion or access charge scheme should be considered.72

55.Heathrow ltd. set out a package of measures aimed at reducing the use of motor vehicles to access the airport. They told us that their analysis and that of the Commission showed public transport could increase to over 50% of journeys by 2030 and possibly as high as 60% with the right measures.73 These included reducing prices on Heathrow Express, expanding the airport travelcard scheme and employee car share scheme and promoting the use of low emissions taxis and buses.74 Heathrow ltd. also argued that an expanded Heathrow would be better laid out - allowing easier access to the various parts of the airport without the use of taxis or other vehicles.75 Finally, they told us Heathrow would benefit from a number of upcoming public transport schemes including Crossrail, HS2 and the Western Rail Access.76 These factors led John Holland-Kaye to make a commitment to us that:

We will have no more cars on the road as a result of Heathrow expansion.77

56.The difference between Heathrow’s forecast and that of TfL could not have been more stark. TfL estimated that there would be an additional 40,000 journeys on the roads and 112,000 by public transport in 2030 following expansion. Indeed, they argued that these estimates were probably on the low side - citing freight, increased business activity in the Heathrow area and new London population figures released since the Commission’s report as reasons to believe that the figures might be higher.78

57.TfL and the local authorities agreed that Heathrow was trying to pursue the right goal in seeking a level of public transport above 50%. However, they questioned whether it could be achieved within the proposals put forward by Heathrow and the Commission based on past performance, the capacity of the public transport system and the ability to change behaviour.79 They argued that a transport solution to achieve modal shift for Heathrow had to be embedded within an integrated transport solution for west London, it could not be treated in isolation.80

Costs and Funding

58.There was further disagreement about the costs of public transport improvements that would be needed to achieve the levels of modal shift which all sides agreed was desirable. The Commission found:

It is clear that with or without airport expansion, the Government will need to take decisive action to address long-term capacity issues arising from background demand growth. This may involve the provision of new infrastructure, demand management, or a combination of the two. The additional challenges presented by airport expansion are not a transformative factor that would significantly change the scale of these challenges.81

59.Heathrow ltd. told us they were willing to pay a proportionate share of the costs - as they had for previous schemes - and had set aside over £1 billion in funding as their contribution towards public transport improvements.82 The Airports Commission estimated around £5 billion in total capital costs for surface access.83 TfL told us it would cost £15-£20 billion to fund the total transport infrastructure required.84

60.Heathrow ltd. disputed the TfL figure in our evidence session, saying the figure included the whole of Crossrail 2 and other projects not immediately arising from Heathrow expansion.85 TfL subsequently wrote to the Committee to say that the figure did indeed reflect their estimate of the surface access infrastructure “required” by an expansion of Heathrow. They did not, however, deny that the improvements would have benefits for non-airport users or claim that the costs should be entirely borne by the airport.86

61.The aspiration of moving the majority of journeys to public transport with no increase in road traffic is shared by all. Transport for London told us this would require large-scale modal shift of the scale seen in central London over the last 15 years.87 However, there is no agreement between them and the Commission over the extent of infrastructure improvements required to achieve this, the resulting costs or, by implication, the extent to which individual parties would meet those costs. Before the Government decides to go ahead with Heathrow expansion it should set out its assessment of what would be required in terms of infrastructure improvements, agreed responsibilities for funding and milestones for completion. This should be part of a wider transport strategy for West London to minimise the risk of unintended consequences. The Government must make a binding commitment that Heathrow will fund the infrastructure improvements necessary to accommodate an expanded Heathrow.

40 Statement on the evidence for the effects of nitrogen dioxide on health, Committee on the Medical Effects of Air Pollution, 2015; Walton, H., et al. (2015) Understanding the Health Impacts of Air Pollution in London. A report for Transport for London and the Greater London Authority

41 Airports Commission, Chapter 9; Heathrow Ltd. written evidence

42 Airports Commission Final Report, page 27

43 Oral evidence, Cllr Amrit Mann, Q 43; Air Quality Local Impact Assessment, Airports Commission, Table G5

44 Mirocgrams per meter cubed.

45 Airports Commission Final Report, para. 9.54; The Clean Air Handbook, Client Earth, April 2014

46 Airports Commission Final Report, para 9.77

47 Oral evidence, 4 November 2015, Q 103

48 Oral evidence, 4 November 2015, Q 105; Written evidence, Bureau Veritas UK

49 Airports Commission, Final Report, paras. 9.81 - 9.82

50 Airports Commission Final Report, para. 9.87; Written evidence, Heathrow Airport Ltd., 3.2.12

51 Heathrow supplementary written evidence

52 Airports Commission Final Report, para. 13.65

53 Oral evidence, 14 October 2015, Q 41 and Transport for London written evidence; see also Q 38 and written evidence, Aviation Environment Federation; written evidence Communities Against Increased Aircraft Noise; Friends of the Earth England and Wales; Gatwick Airport; Richmond and Twickenham Friends of the Earth

54 Oral evidence, 14 October 2015, Q 48

55 Written evidence, Clean Air in London, para 6

56 Sir Howard Davies, letter to the Secretary of State for Transport, 7 September 2015

57 Oral evidence, 4 November 2015, Q 188

58 Consultation on Draft Plans to Improve Air Quality, Department of Environment, Food and Rural Affairs, para. 40

59 Client Earth, written evidence; other witnesses also argued that the change in target date for compliance introduced uncertainty around the Commission’s analysis - for example, written evidence, Manchester Airports Group, South Buckinghamshire Council.

60 Written evidence, Maureen Williams, Stephen Clark; also Friends of the Earth England and Wales and Friends of the Earth Twickenham and Richmond

61 Oral evidence, 14 October 2014, Q 47

62 Oral evidence, 4 November 2015 Q 175

63 Heathrow Ltd. Written Evidence; Oral evidence, 4 November 2015, John Holland-Kaye, Q 103

64 Written evidence

65 Written evidence, para 2.26

66 Hounslow Borough Council, written evidence, para. 2.11

67 Heathrow Airport, written evidence, Figure 3.2

68 Oral evidence, 4 November, Q 121

69 Written evidence, 2M, para. 2.15 - 2.17

70 Hounslow Borough Council, written evidence para. 2.9 also Oral Evidence, 14 October 2015, Q 58

71 Airports Commission Final Report, page 28

72 Airports Commission Final Report, page 32

73 Heathrow Ltd, written evidence; Airports Commission Final Report, para. 8.27

74 Supplementary written evidence, Heathrow Ltd.; Oral evidence, John-Holland Kaye, Q 106

75 Oral evidence, John-Holland Kaye, Q 106

76 Oral evidence, John-Holland Kaye, Q 119-120; written evidence and supplementary written evidence, Heathrow Ltd.

77 Oral evidence, John-Holland Kaye, Q 106

78 Written evidence, Transport for London; Oral evidence, Richard Di Cani, Q 51

79 Oral evidence, 14 October 2015, Q 54-56; Written evidence, 2M, section 3

80 Oral evidence, Cllr Mann, Daniel Moylan Q 57

81 Airports Commission Final Report, para. 8.25

82 Oral evidence, John Holland Kaye, Q 117

83 Airports Commission, Final Report, Table 11.2

84 Oral evidence, Richard di Cani, Q 53

85 Oral evidence, Matt Gorman, Q

86 Transport for London, supplementary written evidence

87 Richard di Cani, Oral evidence, 14 October 2015, Q 55

© Parliamentary copyright 2015

Prepared 30 November 2015